University of Southern California law professor Mary Dudziak appeared Wednesday on MSNBC to explain why she believes the United States has been in a permanent state of war.

“The idea of wartime is doing a lot of work in American politics,” she said. “The way we think about history is history passes through two different kinds of time, from wartime to peacetime to wartime et cetera.”

“That’s the way we learn about it in school, that’s the way that we imagine it. When we use to concept of wartime, we assume that wartime is by definition temporary.”

But Dudziak noted that over the past 100 years, there had been few times when the United States was not engaged in a some sort of military conflict.